Blown Head Gasket -
05-07-2002, 08:26 PM
#16
The reason why I brought up that suggestion was because I know someone who went that route (same problem, all headstuds intact), and it stopped the leak. He has had it like that for about 1000 miles and no leaks. It would just be a shame to spend all that money and be w/o your car for a month or so for a stupid leak. If you were planning a rebuild in the near future, then it would make sense.
05-07-2002, 08:47 PM
#17
Three Wheelin'
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T.P. - I actually liked your suggestions - seems worth a try to me. But my wife says no - get it fixed permanently. So now I have to figure what else to do while the engine is open.
05-07-2002, 10:37 PM
#18
Nordschleife Master
[quote]Originally posted by Geoffrey:
<strong>Luke,
For longevity reasons, it is not good to run an air cooled Porsche engine past 1bar boost. Porsche seemed to limit its race cars to 1.6/1.7 bar boost but that was with special headgaskets and sealing surfaces.</strong><hr></blockquote>
I am not an aircooled expert, but hopefully (if I pay close enough attention to you guys ......) I might get there.
I assume you are limiting an aircooled motor to 1 bar because of heat at that pressure, right? Wouldn't the amount of heat have to do with the backpressure. KKK hotsides are notorious for generating lots of backpressure (or so I am told) This is why the 951's have wastegate problems and this is also why I dont understand why you guys upgrade to a larger kkk (k27 or 29 variant)??? WHy not a garret?
<strong>Luke,
For longevity reasons, it is not good to run an air cooled Porsche engine past 1bar boost. Porsche seemed to limit its race cars to 1.6/1.7 bar boost but that was with special headgaskets and sealing surfaces.</strong><hr></blockquote>
I am not an aircooled expert, but hopefully (if I pay close enough attention to you guys ......) I might get there.
I assume you are limiting an aircooled motor to 1 bar because of heat at that pressure, right? Wouldn't the amount of heat have to do with the backpressure. KKK hotsides are notorious for generating lots of backpressure (or so I am told) This is why the 951's have wastegate problems and this is also why I dont understand why you guys upgrade to a larger kkk (k27 or 29 variant)??? WHy not a garret?
05-08-2002, 09:16 AM
#19
Nordschleife Master
Luke,
If you think about the engine design, a 951 for example has a one piece engine block which gives it structural stability especially from front to back. An aircooled Porsche engine has a split case, individual cylinders AND heads. The cam towers bolt and hold the engine together from front to back. Also, there is a lot of heat generated from any turbo and the 911 is only cooled by the air passing between the fins and the oil running over the components so it is more affected by temperature than a watercooled type engine. Also, the pressure exerts an extreeme amount of stress on the engine. I don't know much about the KKK turbochargers except that you can mix and match many different hot and cold housings. I personally run a Garret T04S which is about the same size as a KKK K29, except in my opinion more effecient. I acheive full 1 bar boost at 2800rpm in any gear (electronic wastegate control the MoTec) so there is not as much lag as perhaps a car with a K27 which is smaller and lighter.
If you think about the engine design, a 951 for example has a one piece engine block which gives it structural stability especially from front to back. An aircooled Porsche engine has a split case, individual cylinders AND heads. The cam towers bolt and hold the engine together from front to back. Also, there is a lot of heat generated from any turbo and the 911 is only cooled by the air passing between the fins and the oil running over the components so it is more affected by temperature than a watercooled type engine. Also, the pressure exerts an extreeme amount of stress on the engine. I don't know much about the KKK turbochargers except that you can mix and match many different hot and cold housings. I personally run a Garret T04S which is about the same size as a KKK K29, except in my opinion more effecient. I acheive full 1 bar boost at 2800rpm in any gear (electronic wastegate control the MoTec) so there is not as much lag as perhaps a car with a K27 which is smaller and lighter.
05-08-2002, 10:15 AM
#20
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It's not just the heat, but also the A/F ratio at that boost. Anything higher than 1 bar without an upgraded fuel delivery system is going to cause the engine to run lean. Factory cars are not running CIS.
